[Zope] python call escaping HTML

[cyrille]

hello,
I'm shure it's a often asked question ... sorry ;o{

How to get python returned string to be not html escaped, just a raw 
string ?
I call a product instance like this :
    <span tal:replace="python: here.meteo" />
the return value is a html string, and Zope is escaping it like 
character '<' is rewritting as '&lt;'

is there a tal syntax that I can use to tell Zope to not escape python 
output ???

thanks,
Cyrille